Truncated cone vs FMJ!

S

Super-Dave

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I have read on the internet that truncated cone actualy penetrated deeper and causes more damage than FMJ ball.

Is this true?

Does not make sense to me.
 
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I see no reason to believe that. The flat meplat will drain a lot of energy by violently displacing tissues sideways, where the needle points of many fmj will slide through transferring little energy, and rounded ball ammo will impart a level somewhat between, and give penetration somewhere in between, given equal diameter, velocity, and weight.
 
I can't speak to truncated shapes out of personal experience, and I assume you mean FMJ ball, and Truncated FMJ. I can tell you for sure that Keith SWC's and LBT along with other flat nosed stuff, which have much larger meplats than any truncated semi auto round, penetrate like the dickens. Keith knew this, and John Linebaugh knows this now, in addition to many handgun hunters.

The truncated FMJ fodder I have examined had pretty obviously radiused transitions between the meplat, shoulder, and shank areas. I really think that if a test were done, no significant difference would be found between the two assuming all other factors were identical. It really isn't something I would waste much thought on.
 
penetration

Agree w. jhenry. Check out the data from brassfetcher.com on ballistic gel tests of many cartridges.
 
Back in the early '90s some gun magazine conducted an experiment using 12" calibrated ballistics gelatin blocks, two chronographs; one in front to register impact velocity, and a chrono in the rear to register the exit velocity of the bullet.

Using 4" barrelled .38 Special and .44 Special service revolvers, they concluded that RNL bullets would tend to tumble towards the middle of the block after shedding some velocity, increasing permanent crush cavity & overall wound severity; and the flat-meplate truncated-cone bullets would tend to tumble only towards the end of the block with less overall crush cavity because the bullet maintained a straight line of penetration

Both bullets exited the blocks at approximately the same velocities, with the RNL exiting vertical or horizontal, and producing slightly greater overall wound trauma.

It makes sense to me because hunters wanting maximum penetration on big-game that can run you over like a bus typically use premium hardcast lead or flat-nose bullets driven to moderate or high velocity levels. I've read that 2300-2400 fps is the ideal velocity for big critters like elephant hippo and cape buffalo
 
I used to get Fiocchi .357 142g truncated cone FMJ for about $13 a box. It went through every paper target I shot at.

I always wonder the same weather is penetrates better than ball ammo. Being semi pointy I would think it would, but not sure though.
 
Truncated cone denotes a SPECIFIC bullet shape with a flat nose. The overall shape of the bullet is pretty tightly bounded by the form factor (not a great explanation). What I'm really saying is that from different manufacturers, there's not going to be a tremendous amount of difference in the overall size of the size of the flat nose, the angle or length of the cone, etc., of bullets from different manufacturers as long as they're the same weight.

Full metal jacket denotes a bullet composition, but NOT a shape.

There's no way to adequately compare the two.

A full metal jacket pistol bullet can be quite pointed and elongated, or it can be quite blunt.

For example, a 9mm bullet with a rather elongated profile:

287146.jpg



And the other extreme, the .455 Webley Automatic FMJ.

800px-455_Webley_auto_cartridge.JPG
 
Not a clue on penetration but in my guns TC is a bit more accurate and instinct tells me the flat meplat has to provide a bit more shock on initial contact. However when the bullet has finally finished up its tour of the target its a moot point and the one getting shot won't be able to tell the difference. I only use RN bullets for most of my loads because of price, not because of any imagined superiority or advantage. Just dos centavos from an old dinosaur.
 
Mike Irwin

Truncated cone denotes a SPECIFIC bullet shape with a flat nose.
Click to expand...

Key word, "Cone", I did look at my TC .357 Fiocchi's and they have a flat nose, but they still look pointy, so in point is very small in contrast to the overall bullet width, at least these Fiocchi's.

Now, if you look a Corbon .357 200g Hard cast, those are flat nosed but I don't think they're TC bullet's. Sorry I don't have photo but are rounded from the bullet width to the flat nose tip if that makes sense.:rolleyes:
 
You will have some variation, Elvis, from manufacturer to manufacturer.

But the term truncated cone is much more specific at defining a bullet's shape than simply saying Full Metal Jacket.

FMJ indicates only that the bullet has a jacket.

Truncated Cone means that the bullet has a flat nose. No getting around that.

You can have FMJ truncated cone bullets. You can have FMJs with a wadcutter style profile, too, although they're not really common.
 
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